18.SimpleBankSystem.cpp

class Bank {
public:
    int n;
    vector<long long> bal;

    bool validAc(int acc) {
        if (acc > 0 && acc <= n)
            return true;
        else return false;
    }

    Bank(vector<long long>& balance) {
        bal = balance;
        n = balance.size();
    }
    
    bool transfer(int account1, int account2, long long money) {
        if (!validAc(account1) || !validAc(account2) || bal[account1-1] < money)
            return false;
        
        bal[account1-1] -= money;
        bal[account2-1] += money;
        return true;
    }
    
    bool deposit(int account, long long money) {
        if (!validAc(account))
            return false;
        
        bal[account-1] += money;
        return true;
    }
    
    bool withdraw(int account, long long money) {
        if (!validAc(account) || bal[account-1] < money)
            return false;

        bal[account-1] -= money;
        return true;
    }
};

/**
 * Your Bank object will be instantiated and called as such:
 * Bank* obj = new Bank(balance);
 * bool param_1 = obj->transfer(account1,account2,money);
 * bool param_2 = obj->deposit(account,money);
 * bool param_3 = obj->withdraw(account,money);
 */